Effects of windstorm-induced forest loss and variable reforestation on bird communities
We study the response of breeding bird communities to windstorm-induced forest loss and different reforestation strategies in one of Central Europe’s largest contiguous windthrow areas created by storm Kyrill in 2007. A decade after the disturbance, we compared bird species diversity, population densities and community composition in replanted beech, replanted conifers and secondary succession (all salvage-logged after the storm), with undisturbed mature Norway spruce as a control, in the setting of a natural experiment.
Of the stands blown down, 95% were Norway Spruce. Reforestation strategies vary in the area, with Spruce and non-native conifers planted on twice the area that was replanted with European Beech. Large areas are still dominated by successional tree species a decade after the storm, especially birch, mirroring recommendations of sub-national forestry agencies to include secondary succession in future forest development. Birds respond strongly to windstorm-induced forest loss, with a pronounced community turnover. Species associated with high conifer stands reach significantly lower densities in disturbed areas. Replanted areas are characterized by mostly ubiquitous bird species. Areas dominated by secondary succession, especially birch, are characterized by high densities of long-distance migrants (often species of conservation concern) and shrubland species, among them several indicator species (published results).
In the coming years, we will resurvey the sample plots regularly to monitor bird responses to vegetation succession in windthrow areas as well as the effects of spruce diebacks after recent bark beetle outbreaks.
The project is a collaboration with Landesbetrieb Wald & Holz Nordrhein-Westfalen, Forstamt Balve.